The answer would be the average number of people in a given area.
Italy was geographically separated from the other countries in Europe because of the Alps. It is a vast mountain range system that stretches 750 miles along Austria, France, Germany, Italy, Liechtenstein, Monaco, Slovenia, and Switzerland. The Alps' shape is crescent.
Declining birth rate, all the pollutions, crowding , and house shortage
I think it is
sand
silt
clay